Download the latest TZ file from "https://www.iana.org/time-zones"

Log into the Junos device and open shell mode: 
            # start shell

Create a tz directory in the /var/tmp and navigate to that directory 
            # mkdir /var/tmp/tz
      # cd /var/tmp/tz

Upload the File Via FTP/SFTP to the newly created directory.

Extract the file with extension tar.lz
            # start shell user root
          # Tar -xvf tzdata2024a.tar.gz

After extracting the file, you would be able to see the TZ files from various continents and time zone.

Select the names of time zone files to compile and feed them to the following script.
For example, to generate asia tz files:
            # /usr/libexec/ui/compile-tz asia   
            # zic asia

             # cp asia/var/db/zoneinfo/

Using the CLI, configure the router or switch to enable the use of the generated tz files as follows:
             # set system use-imported-time-zones
             # commit
                  
Now the newly generated TZ file would be available in /var/db/zoneinfo and you can set the time zone:-
            
 # set system time-zone
 Possible completions:
 <time-zone>  Time zone name or POSIX-compliant time zone string
 Asia/Aden
 Asia/Almaty
 Asia/Amman
 Asia/Anadyr....